Method for producing amorphous quaternary nitrogen compositions



United States Patent Ofiice 3 Claims. 01. 260-268) INTRODUCTION This isa division of application Ser. No. 131,490; now U.S. Patent No.3,239,521, filed Aug. 15, 1961, and is a continuation-in-part ofcopending application Ser. No. 50,877, now U.S. Patent No. 3,239,549,filed Aug. 22, 1960.

This invention generally relates to the production and use of solublesodium-free hydroxylated organic quaternary nitrogen silicates. In oneparticular embodiment this invention relates to the production and useof-sodiumfree tetraethanol-ammonium silicates and derivatives thereof.

BACKGROUND Water-soluble alkali metal silicates are favored componentsof (1) refractory and rapid-setting cements, (2) inorganic coatingshaving a refractory or weather-resistant character and (3) numerousadhesives. However, in certain uses they have drawbacks which areassociated with the alkali metal component, and it has long been anobjective to prepare a soluble silicate useful in these various fieldswhich is free of any alkali metal component. For instance, in arefractory cement the presence of the alkali metal salt lowers thesoftening point of the cement because of the fluxing characteristic ofthe salt. Efforts to overcome this have been made by increasing thesilica ratio of the soluble silicate but some alkali metal salt alwaysremains even after neutralization and excessive washing. Furthermore,the alkali metal silicate solutions increase in-viscosity rapidly as theconcentration increases at high silica ratios so that in commercialsolutions prepared at-about the 4-0SiO :Na O ratio the solid contentwill be no higher than 30%. Furthermore, where the silica ratio is high,the softening point of the anhydrous sodium silicate also is high.

One aspect of this invention broadly involves the discovery of solubleamorphous sodium-free organic N-containing silicates which overcome theaforementioned drawbacks of soluble alkali metal silicates. In anotherspecific aspect of the invention, I believe that I am the first personto discover sodium-free tetraethanolammonium silicate and methods forproducing same. The tetraethanolammonium silicate which I havediscovered does not appear to crystallize readily since I have not beenable tv obtain crystals after many attempts.

THE INVENTION This invention broadly encompasses amorphous compositionshaving the general oxide formula with continuously variable ratios:

X(N,,R O-YSiO -ZH 0 In the above formula:

N represents a nitrogen atom;

n is a small integer, less than and preferably less than five;

X, Y and Z represent numbers defining the relative amounts of each ofthe component parts of the compound. X is 1, Y is preferably between 0.5and 20, and

Z is preferably between 0 and 99, and wherein up to four R groups areassociated with each N;

R represents organic radicals having between 1 and 20 carbon atoms, atleast two of said organic radicals consisting of omega hydroxy alkylgroups (preferably two or more of these R groups are ethanol groups andthe others derivatives of ethanol groups);

p is at least 4 and up to 4n and is equal to the number of R groups; and

sis an integer from 1 to p, indicating the number of different types ofR groups.

According to one specific embodiment the invention relates to theproduction of amorphous compositions having the formula:

wherein N, X, Y and Z have the significances noted above and R R R and Rrepresent alkanol radicals containing between about 1 and 20 carbonatoms.

The tetraethanolammonium silicates of this invention can form aqueoussolutions of over 50% solids content at viscosities at which thesolution is readily useful (such as 2 poises). Such solutions may haveas high as 15 moles of SiO to 1 mole of organic alkali (i.e. the organicbase) and yet be readily soluble and have a relatively low melting pointwhich is representative of organic compounds rather than the inorganicsalts. The organic base portion can be readily removed, leaving a silicacement in place. This may be accomplished either by heating or byneutralization and removal of the soluble organic base salt. Thus, thisnew compound and its derivatives have an important place in theformulation of refractory and rapidsetting cements as well as incoatings for roofing granules and shingles, in special adhesives, ininvestment molds for casting metals, and the like.

I have found that tetraethanolammonium silicates and their derivativesform stable, water-free compositions which are easily soluble in water.These compositions have a range of mole ratio of SiO to quaternary ionfrom about 0.5 to 1.0 (i.e. a mole ratio of SiO to quaternary oxide ofabout 1 to 2), or lower, to about 15 to 1 (i.e. about to one on thequaternary oxide ratio), or higher. These pure compositions vary fromviscou oily liquids at the lower ratios to pliable solids in the higherrange and, finally, to brittle solids. At a ratio of about 21, thedehydrated solid becomes insoluble. These compositions below about ratio15 are miscible in all proportions with water. The silica is present inaqueous solutions of such compositions largely as crystalloidal silicaunder equilibrium conditions. They have a relatively high pH but aviscosity much lower than that of a sodium silicate solution having asimilar solids content and silica ratio. Soluble silicate solutionsabove a molecular ratio of 4.0 are so difficult and costly tomanufacture and so relatively unstable at high concentrations that theyhave never been commercially available. Thus, in the sodium system aratio of 4.0 has been considered the maximum. As pointed out above, this4.0 ratio material can be concentrated usefully only to about 30% solidsWhereas the 12 ratio organic base silicate will readily form solutionsof reasonable viscosity at more than solids content.

METHODS OF PREPARATION The compounds of this invention may be preparedin a number of ways. Such methods include, for example:

(a) Removing the alkali metal ion from alkali metal hydroxylatedquaternary ammonium silicates by use of a suitable base exchange resin;

(b) dissolving sodium-free silica in sodium-free hydroxylated organicquaternary ammonium bases;

Patented Aug. 29, 1967 (c) dissolving sodiumfree silica in sodium-freetetraethanolammonium silicate solutions;

(d) the sodium may be leached from the less soluble sodium hydroxylatedquaternary ammonium silicate crystals;

(e) reacting ammonia or an amine and ethylene oxide with finely dividedsilica hydrate or silica gel, or a colloidal silicia sol.

The following examples are illustrative of the invention:

Example 1 PREPARATION OF SODIUM-FREE HYDROXYLATED ORGANIC AMMONIUM sILICATEs In a reaction flask equipped with a stirrer, thermometer, alow-temperature reflux condenser and a gas inlet tube, 30 grams ofaqueous 29% NH solution were admixed with 1110 grams of Ludox LS. Nogelation or coacervation occurred, and 92.5 grams of ethylene oxide weredistilled into the agitated mixture through the gas inlet tube. Thetemperature was maintained between 24 and 265 C. The ethylene oxide wasdistilled over in the course of about one hour, and the reaction wascontinued for 6 more hours and then left at room temperature overnightin a closed vessel. The next morning the water was distilled off byvacuum distillation. Part of the solution was removed when it contained50% SiO and the remainder was taken to dryness.

In the 50% solution, the analysis was 14.39% of quaternary ion and52.53% of SiO with a mole ratio of 11.81 of SiO :1. of quaternary ion.This solution had a specific gravity at 20/20 of 1.512 and a viscosityat 20 C. of 2.8 poises. The material taken to dryness was solid buteasily soluble in water, even though the mole ratio was 11.81 SiO to 1of quaternary ion. This corresponds to a ratio of 1.0 quaternaryammonium oxide: 23.6SiO :49.8H O. It was not soluble in methanol orordinary organic solvents. With increasing silica ratio the solubilityin methanol declines.

Following the same procedure, a composition having a mole ratio of about21 was prepared by allowing 444 grams of Ludox HS, 6 grams of aqueous29% NH, and 18.5 grams of ethylene oxide to react. After the reactionwas completed and the mixture contained in a closed vessel overnight,the water was distilled off. This left a solid, white material which wasvery brittle and easily broken into small particles. It appeared to beinsoluble in water. Thus, the limiting ratio at which the solidanhydrous material was completely miscible with water is probably about15 to 16.

Example 2 A sodium-N,N,N',N-tetra (Z-hydroxyethyl) piperazinium silicatemay be prepared either from N,N-bis-(2- hydroxyethyl) -piperazine withsodium silicate and 2 moles of ethylene oxide, or from unsubstitutedpiperazine and 4 moles of ethylene oxide with the sodium silicate. Sucha reaction was carried out by dissolving 34 grams of theN,N'-bis-(2-hydroxyethyl)-piperazine in 300 grams of water and mixingthis with 240 grams of E sodium silicate in the reaction flask. Thereaction was carried out between 23 and 30 C. beginning at the lowertemperature with a clear, yellowish solution. The 36 parts ethyleneoxide were distilled over in 52 minutes, forming a heavy coacervatewhich dissolved in about 20 minutes. The reaction was allowed tocontinue for about 6 hours at which time it was again a clear, yellowishsolution. This solution was kept overnight and crystals had begun toform at that time. 260 grams of water were distilled off and the finalmixture of crystals and solution was put in a refrigerator at about 2 C.overnight. Crystals were then filtered off and were washed four timeswith water. This product had an ignited loss of 74.91% and contained44.08% of quaternary ion, 30.83% of water, 24.16% of SiO with 1.01% ofNa O. When these crystals were washed with alcohol instead of water, theNa O content was about 4.5%. The product containing 1% of Na O had noreal melting point but became damp at about C. and turned brown withoutmelting at about C.

When the product was washed 10 additional times, with a total of 1500ml. of water to 5 grams of the product, the residue was found to have anignited loss of 72.85% with 35.31% of quaternary, 37.54% of H 0 and26.41% of SiO with only 0.09% of Na O. Thus this product has a moleratio of 3.3 SiO to 1.0 of quaternary ion and 15.6 moles of H 0. Sincethe quaternary ammonium ion contains two basic nitrogens the oxide ratiohas exactly the same ratio as the ion ratio, that is 1 quaternaryammonium oxide:3.3SiO :15.6H O. It decomposes without melting at 118 C.This final product is somewhat soluble in water and gives a solutionwith a pH of about 10.5.

A number of the materials used in the preceding examples are describedas follows:

The alkali metal silicates, supplied by the Philadelphia Quartz Co., arecharacterized in the following table:

Trademark E:

Ratio, percent Na O:SiO 1:3.22

N320, percent 8.60 SiO percent 27.7 H O, percent 63.6

Ammonium hydroxide was the 28-30% aqueous Reagent Grade supplied byAllied Chemical Co.

The ethylene oxide with a purity of about 99.5% was supplied by MathesonCompany, Inc.

Two colloidal silica sols sold by the Du Pont de Nemours Co. as Ludox HSand Ludox LS had the following composition:

ANALYTICAL PROCEDURES In analyzing the quaternary ammonium silicates,special procedures are necessary.

Ignition l0ss.--The ignition loss is determined with a sample ofquaternary silicate weighing one gram. This sample is heated in acovered platinum crucible, raising the temperature very, very slowly. Ifthe ignition is carried out too fast, silicon carbide forms and it isalmost impossible to burn it off. Therefore the crucible is heatedextremely slowly on one side until all of the organic matter has charredcompletely. This procedure takes about one hour, then the heat isincreased slowly to the full blast of a Tirrel burner and continueduntil the sample has turned completely to either white powder or a clearwhite melt. This takes about two more hours. When the sample is white incolor it is transferred to a Fisher burner and heated full blast for afurther half hour.

Quaternary ammonium base.The nitrogen content is determined using theKjeldahl procedure with special acid. Heating is continued until theoriginally dark solution becomes clear and no dark specks remain. Thisdigestion period takes between 3 to 24 hours, depending on thecomposition. After the contents are cooled to room temperature, 100 ml.distilled water are added carefully through the reflux tube whileswirling the contents. Then a few Alund-um boiling stones are added anda magnetic stirrer. The reflux glass tube is removed and the flask isconnected to the distillation equipment. The end of the condenser dipsinto a receiver containing 100 ml. of distilled water with excess 0.2-normal HCl over the expected equivalent of ammonia. About 130 m1. of 6-normal sodium hydroxide are added to the reaction flask through adropping funnel while stirring with a magnetic stirrer. When all of thesodium hydroxide is added, the reaction mixture is headed for an hour tovigorously boiling. The ammonia formed during the digestion is drivenover into the acid solution and after completion the free hydrochloricacid is back titrated with 0.2-normal NaOH.

Silica determinati0n.-Silica in solution may be determined using theusual volumetric method and the gravimetric method maybe used forinsoluble silica (Vail,

Soluble Silicates, vol. I, p. 40.)

PRODUCT PROPERTIES Viscosity.-The aqueous solutions of the sodium-freeproducts in accordance with this invention are quite alkaline andconcentrated solutions are quite viscous. For instance, a solution of74% of a tetraethanolammonium silicate having a ratio of 0.53 SiO toquaternary ion (i.e. 1.06 S to 1 quaternary ammonium oxide) had a pH of12.8 and a viscosity at 20 C. of 8.0 poises. At 50 C. the viscosity haddropped to 1.1 poises. On the other hand, a solution of a productcontaining 70% of 8.7 ratio (SiO to quaternary ion or 17.4 SiO toquaternary ammonium oxide) material with 30% of water had a pH of 11.08and a viscosity at 20 C. of 14.1 poises; at 50 C. the viscosity was 6.0poises. A solution containing 50% silica prepared from atetraethanolammonium silicate of the mole ratio of 11.8 SiO to 1.0quaternary ion (or 23.6 SiO to 1 quaternary ammonium oxide) had aviscosity at 20 C. of 2.8 poises.

Gelation vs pH .A sodium-free quaternary tetraethanolammonium silicatehaving a ratio of 2.74 SiO :1.0 quaternary ion (or 5.48 SiO to 1quaternary ammonium oxide) and a concentration of 42.08% SiO was dilutedwith water to 30% SiO and gradually neutralized With sulphuric acid. Theinitial pH was 11.3. At a pH of about 10.5, the mixture became veryviscous but did not gel, and gradually the pH rose again to 10.8 duringthe course of 24 hours. When this was again reduced to a pH of 10.5, themixture appeared to gel in about 2 to 4 minutes but reliquefiedovernight, forming a clear, very viscous solution. Again, at a pH of10.4, a gel-like structure formed after 1.5 minutes, but this alsoreliquefied after 4 days, forming a clear and viscous solution. At a pHof 9.85 a gel formed which did not redissolve or reliquefy over a periodof more than 2 weeks.

On the other hand, a 3% solution was treated with 3% H SO with a pHlowered gradually to about 2. In these solutions no gel formed, butrather a finely divided silica. This lack of gelation must be related tothe fact that the silica in these solutions is crystalloidal rather thancollodial.

Flms.-A sodium-free tetraethanolammonium slicate having a mole ratio of8.7 Si0 (or 17.4 SiO to 1 quaternary ammonium oxide) had a concentrationof 45.7% Si0 and 17.02% of quaternary. Films were cast on small metaldishes and dried at room temperature, 100, 200, 400 and 800 C. Theweight loss and solubility of these films were determined. The alkali inthe films remained quite soluble even after drying at 100 C., but ondrying to 200 C., and especially above 200 0., much less alkali could bedissolved out. The silica in these films, even those dried at roomtemperature, was rather insoluble. The amount of silica dissolved byboiling 2.5 grams of a film dried at roomtemperature in 50 ml. of water15 minutes was 2.7%. This was reduced to 1.2% after heating at 400 C.,and to less than 1% after heating at 800 C.

A more alkaline material having a ratio of 4.8 (or 9.6 Si0 to 1quaternary ammonium oxide) was used as a solution containing 41.0% SiOand 27.55% of quaternary ion. 59% of the silica was soluble after dryingat C. butafter dryingat 200. C. only 2.6% was soluble, and at 400 C.,and higher, less than 1% was soluble. These films had no adhesion tometal or glass. The quaternary ion was soluble in both films aftercuring at 100 C. 'At 200 C., and above, it appears that the organic ionbreaks down and evaporates to some extent. About 5.0% was lost by curing30 minutes at 200 C., and this appears to be more noticeable in theratios containing higher quaternary nitrogen alkali. The more siliceousfilms crack completely when dried at room temperature for 16 hours,whereas low ratio films, for instance those having a ratio of about 4,form hard, smooth surfaces at room temperature which do not change foralmost 4 days, at which time a light cracking around the edges isobserved. Neither do .they crack at 100 C. However, on curing at 200 C.these films do crack and turn tan in 5 minutes. The films all break downand turn brown when cured at 400 C. and cannot be scrubbed off theplates.

The film .stability may be increased by adding material such as urea orPolyox WSR 35, a high molecular weight ethylene oxide polymer sold byUnion Carbide Chemicals Co. Glycerine was also good in the more alkalineratio materials. The same may be said for cane sugar, sorbitol andhexamethylenetetramine.

Adhesives.-An adhesive solution was prepared from a sodium-freetetraethanolammonium silicate having a silica ratio of 5.44 (or 10.9 SiOto 1 quaternary ammonium oxide), with a total solids content of 68.27%.The viscosity at 20 C. was 2.33, and the pH was 11.4. After setting atroom temperature, B flute single face kraft board bonded with thisadhesive had a pin adhesion strength of 43.4 pounds per 12 inches offlute tip. Setting the bond at higher temperatures reduced this strengthas, for instance, at 94 C. the strength was only 37.4 lbs., and at 232C. the strength was only 8 lbs. per 12 inches of flute tip. In allcases, the Wet strength was less than one-half pound.

Apparently because of the crystalloidal nature of the solutions, thosesolutions having higher silica ratios gave weaker bonds.

The use of quaternary ammonium silicates .for water treatment.-F0r sometime in the water treatment field there has been a need for a solublesilicate which could be used in the form of dry feed for the formationof activated silica sols applicable as coagulant aids in the treatmentof raw and waste waters. It has now been found that dry solublesilicates of both the sodium tetraethanolammonium silicate and thesodium-free tetraethanolammonium silicate, as well as other organicsilicates of similar type, are very effective in the formation of solswhich act as coagulant aids. It is expected that acid salts could becombined with these solid organic alkalies and, if desirable, clay orother forms of weighting agent might be added, thus forming a prepareddry material to be used with dry feed equipment in the formation ofcoagulant aids based on activated silica. Such a formulation would makeunnecessary the purchase of expensive units now required for thepreparation of sols from liquid raw materials.

The alkali metal silicates and alkali metal quaternary ammoniumsilicates will form stable solutions with insignificant amounts ofmost'water miscible organic solvents.

For instance, a solution of sodium silicate having a mole ratio of 1NaO:3.22SiO- and containing 15% Si will accept only about 0.5% of eithermethanol, ethanol, isopropanol, acetone, dioxane or tetrahydrofu-ran. Asodium tetraethanolammonium silicate with a mole ratio of lNa O:1.1quarternary ion:3.9SiO (or lNa O:0.55 quaternary ammonium oXide:3.9SiOin an aqueous solution with SiO will accept less than 1% of the abovewater miscible solvents. On the other hand, alkali freetetraethanolammonium silicates with mole ratios varying from 1quarternary ion:2.74SiO to 1:10.42 (or 1 quarternary ammoniumoxide:5.48SiO to 1:20.84) in aqueous solutions containing 1'5 SiO willaccept from 30 to 80% of the above solvents, and such aqueous solutionscontaining 50% SiO will accept from to 40% of these solvents.Miscibility increases with decreasing silica concentration and ratio. Italso tends to decrease in the order methanol, ethanol, isopropanol,acetone, dioxane, tetrahydrofuran. These results suggest the applicationof my new sodium-free quarternary ammonium silicates in paints, coatingsand liquid detergent systems, for example, in which soluble silicateswere never compatible heretofore.

In the foregoing specification, wherever the term sodium is referred toit will be understood that the result would be substantially the samewhen using other alkali metals such as potassium, lithium, etc.

What is claimed is:

1. The method of producing an amorphous quaternary nitrogen compositionhaving the formula:

wherein X, Y and Z represent numbers defining the relative amounts ofeach of the component parts of the compound and X is 1, Y is between 0.5and 20, and Z is between 0 and 99, and R R R and R represent alkanolradicals containing between about 1 and 20 carbon atoms, Whichcomprises:

(a) starting with the known alkali metal salt of the above composition,

(b) leaching the alkali metal ion from the quaternary ammonium silicatecrystals with an aqueous liquid, and

(c) recovering a substantially alkali metal-free amorphous quaternarynitrogen composition of the above formula.

2. A method according to claim 1 wherein R R R and R are each ethanolradicals.

3. The method of producing N,N,N,N-tetra-(2-hydroxyet'hyl) piperaziniumsilicate which comprises:

(a) starting with the sodium salt of the above composition,

(b) leaching the alkali metal ion from the quaternary ammonium silicatecrystals with an aqueous liquid, and

(c) recovering a substantially alkali metal-free amorphous quaternarynitrogen composition of the above formula.

References Cited UNITED STATES PATENTS 2,689,245 9/1954 Merrill260-448.2 3,239,521 3/1966 Weldes et al. 260-268 3,239,549 3/1966 Weldeset al 260-268 FOREIGN PATENTS 709,634 6/1954 Great Britain.

ALEX MAZEL, Primary Examiner.

HENRY R. JILES, Examiner.

JAMES W. ADAMS, Assistant Examiner.

1. THE METHOD OF PRODUCING AN AMORPHOUS QAUATERNARY NITROGEN COMPOSITIONHAVING THE FORMULA:
 3. THE METHOD OF PRODUCINGN,N,N'',N''-TETRA-(2-HYDROXYETHYL)-PIPERAZINIUM SILICATE WHICHCOMPRISES: (A) STARTING WITH THE SODIUM SALT OF THE ABOVE COMPOSITION,(B) LEACHING THE ALKALI METAL ION FROM THE QUATERNARY AMMONIUM SILICATECRYSTALS WITH AN AQUEOUS LIQUID, AND (C) RECOVERING A SUBSTANTIALLYALKALI METAL-FREE AMORPHOUS QUATERNARY NITROGEN COMPOSITION OF THE ABOVEFORMULA.